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Waves, Oscillations & Acoustics

Pitch

The subjective psychoacoustic perception of a sound's frequency by human listeners.

Pitch ∝ f Hz (or Musical Notes) Foundations of Physics

Planck's Constant

A fundamental physical constant that sets the scale for quantum mechanical phenomena, relating photon energy to its frequency.

E = hf, h = 6.62607015 × 10⁻³⁴ J·s J·s Quantum & Atomic Physics

Planck's Law & Blackbody Radiation

The foundational law describing the spectral radiance of electromagnetic radiation emitted by a blackbody in thermal equilibrium.

B_ν(T) = (2 h ν³ / c²) / (e^(h ν / (k_B T)) - 1), E = h ν W / (m²·sr·Hz) Plasma Physics

Plasma Antenna

A radiofrequency antenna that uses ionized plasma gas instead of solid metal conductors to transmit and receive electromagnetic signals.

Conductivity σ_p = (n_e e²) / (m_e (ν_coll - i ω)) MHz / GHz (RF Operating Frequency) Plasma Physics

Plasma Astrophysics

The branch of astrophysics applying plasma physics and magnetohydrodynamics to model cosmic phenomena throughout the universe.

B² / (2 μ₀) ~ ρ v² ~ P_thermal (Cosmic Equipartition) Cosmic Plasma Physics Plasma Physics

Plasma Beta

The ratio of kinetic thermal plasma pressure to magnetic field pressure in a magnetized plasma.

β = p_kinetic / p_magnetic = (n k_B T) / (B² / (2 μ₀)) Dimensionless Ratio Plasma Physics

Plasma Etching

A semiconductor manufacturing process using reactive gas plasmas to selectively remove surface layers from microchip wafers.

Anisotropic Reactive Ion Etching (RIE) nm/min (Etch Rate) & Aspect Ratio Plasma Physics

Plasma Frequency

The natural characteristic frequency of collective electrostatic electron oscillations in a plasma when perturbed from thermal equilibrium.

ω_pe = √(n_e e² / (m_e ε₀)) rad/s (Angular Frequency) Plasma Physics

Plasma Medicine

An emerging field of medical physics applying non-thermal atmospheric pressure plasmas directly to living tissues for therapeutic treatment.

RONS Generation: NO, O₂⁻, H₂O₂, OH•, ONOO⁻ Biomedical Application Plasma Physics

Plasma Parameter

A fundamental dimensionless number in plasma physics measuring the average number of electrons contained within a Debye sphere.

Λ = n_e λ_D³ ≫ 1 Dimensionless Number of Particles in Debye Sphere Plasma Physics

Plasma Sheath

A thin non-neutral positive boundary layer formed in a plasma adjacent to any physical wall or electrode.

V_sheath ≈ (k_B T_e / (2 e)) ln(m_i / (2 π m_e)), v_ion ≥ c_s = √(k_B T_e / m_i) V (Sheath Voltage) & m (Thickness ~ λ_D) Plasma Physics

Plasma Torch

An electromechanical device that generates a high-temperature thermal plasma jet by passing inert or reactive gas through an electric arc…

Thermal Equilibrium T_gas ≈ T_electron ~ 5,000–15,000 K kW to MW (Electrical Power Input) Plasma Physics

Plasma Wave Dispersion Relations

Mathematical equations relating wave frequency ω to wavevector k for electromagnetic and electrostatic waves propagating through magnetized…

CMA Diagram (Clemmow-Mullaly-Allis Wave Mode Classification) ω vs k (Dispersion Relation Curve) Geophysics & Environmental Physics

Plate Tectonics

The unifying geophysical theory stating that Earth's rigid outer lithosphere is divided into major tectonic plates drifting over the…

Plate Motion Velocity v_plate ~ 1–10 cm/year cm/year (Plate Drift Speed) Biophysics & Medical Physics

Poiseuille's Law of Blood Flow

A fluid dynamics equation governing laminar viscous fluid flow through a cylindrical vascular pipe.

Q = (π r⁴ ΔP) / (8 η L) m³/s or L/min (Volumetric Flow Rate) Mathematical & Computational Physics

Poisson Brackets

An algebraic operation between two phase space functions describing time evolution and conservation laws in Hamiltonian mechanics.

{f, g} = ∑ ((∂f / ∂q_i)(∂g / ∂p_i) - (∂f / ∂p_i)(∂g / ∂q_i)) Phase Space Operation Condensed Matter & Materials Physics

Poisson's Ratio

The ratio of transverse lateral strain to axial longitudinal strain in a material subjected to uniaxial stress.

ν = -ε_transverse / ε_axial = -(Δd / d₀) / (ΔL / L₀) Dimensionless Ratio (-1 to 0.5) Foundations of Physics

Polar Coordinates

A 2D coordinate system specifying point location by radial distance r from the origin and angular displacement θ from a reference axis.

x = r cos θ, y = r sin θ, r = √(x² + y²) m, rad Optics

Polarization

The property of transverse electromagnetic waves specifying the geometric orientation of their electric field vector oscillations in space.

E(z,t) = E0 cos(k z - ω t) i_hat N/A Condensed Matter & Materials Physics

Polaron

A composite quasiparticle consisting of a conduction electron (or hole) bound together with its surrounding self-induced lattice…

m*_polaron = m* (1 + α_coupling / 6) Quasiparticle Mass Quantum & Atomic Physics

Population Inversion

A non-equilibrium state of a quantum system where more atoms reside in a higher excited energy state than in lower energy states.

N₂ > N₁ (Excited state density > Ground state density) Dimensionless Condition Biophysics & Medical Physics

Positron Emission Tomography (PET Scan)

A 3D nuclear medicine imaging technique detecting pairs of 511 keV gamma photons emitted during positron annihilation to map metabolic…

Coincidence Detection of 180° Back-to-Back 511 keV Gamma Photons MBq (Activity) & Standardized Uptake Value (SUV) Classical Mechanics

Potential Energy

The stored energy an object possesses due to its relative position in a conservative force field or its structural deformation.

PE_grav = m g h, PE_elastic = ½ k x² J Classical Mechanics

Power

The rate at which work is performed or energy is transferred per unit time.

P = dW/dt = F · v W (J/s)